The present disclosure relates to a transport refrigeration unit (TRU) and, more particularly, to a renewable energy source of the transport refrigeration unit and method of operation.
Traditional refrigerated cargo trucks or refrigerated tractor trailers, such as those utilized to transport cargo via sea, rail, or road, is a truck, trailer or cargo container, generally defining a cargo compartment, and modified to include a refrigeration system located at one end of the truck, trailer, or cargo container. Refrigeration systems typically include a compressor, a condenser, an expansion valve, and an evaporator serially connected by refrigerant lines in a closed refrigerant circuit in accord with known refrigerant vapor compression cycles. A power unit, such as a combustion engine, drives the compressor of the refrigeration unit, and may be diesel powered, natural gas powered, or other type of engine. In many tractor trailer transport refrigeration systems, the compressor is driven by the engine shaft either through a belt drive or by a mechanical shaft-to-shaft link. In other systems, the engine of the refrigeration unit drives a generator that generates electrical power, that in-turn drives the compressor.
When the cargo container is generally stored, and the TRU sits idle for long periods of time, a battery of the TRU may become drained or depleted thus hindering the ability to start the TRU when needed. Moreover, and with current environmental trends, improvements in transport refrigeration units are desirable particularly towards aspects of environmental impact. With environmentally friendly refrigeration units, improvements in reliability, cost, and weight reduction are also desirable.